The present invention relates to a display controller, a display system, and a display control method.
In recent years, a display device using an electroluminescent (EL) element has attracted attention. In particular, since an organic EL panel including an EL element formed using a thin film of an organic material is a self-emission type, a backlight becomes unnecessary, whereby a wide viewing angle is implemented. Moreover, since the organic EL panel has a high response speed in comparison with a liquid crystal panel, a color video display can be easily implemented using a simple configuration.
The organic EL panel is divided into a simple matrix type and an active matrix type in the same manner as the liquid crystal panel. When driving a simple matrix type organic EL panel, grayscale control may be performed using pulse width modulation (hereinafter abbreviated as “PWM”. A display controller performs grayscale control by outputting control signals to drivers (data driver and scan driver) which drive the organic EL panel.
The data lines of the organic EL panel may be driven using a plurality of data drivers. The data drivers are cascade-connected. Display data and various synchronization signals are supplied to the cascade-connected data drivers from the display controller.
Suppose the case where each of the data drivers performs a PWM drive in which grayscale control is performed corresponding to the pulse width within a predetermined period within one horizontal scan period, for example. In the case where the number of data lines of the organic EL panel driven by each of the data drivers is the same (96×3, for example), horizontal display periods in which grayscale control using PWM can be performed are approximately the same. However, since the manufacturing technology of the organic EL panel is immature differing from the liquid crystal panel, the color tone to be represented may differ to only a small extent depending on the product variation. In this case, since the horizontal display period differs for each data driver, the color tone represented by grayscale control differs in each display region driven by each of the data drivers.
In the case where the number of data lines driven by each of the data drivers differs (96×3 and 48×3, for example), the horizontal display period also differs. Therefore, the color tone represented by grayscale control differs in each display region driven by each of the data drivers if the horizontal display period cannot be changed for each data driver.
Therefore, it is preferable that the display controller which controls such data drivers be able to change the horizontal display period for each data driver.